ABCD, arq. bras. cir. dig. vol.24 no.4 São Paulo Oct./Dec. 2011

http://dx.doi.org/10.1590/S0102-67202011000400018

Diverticular disease of the colon is a common
condition in western and developed countries. Its prevalence increases with
age, being present in more than 50% of population aged over 80 in some series.
Distal colon is the mainly stricken part, being the sigmoid colon affected in
up to 70% of the patients6. Otherwise, the occurrence of rectal diverticula
is extremely unusual. According to some series, this condition is found in only
0.07 to 0.08% of barium enema radiographics11,14 and in 2% to 2.4%
of patients with diverticular disease of the colon12,14. Herein,
four patients with rectal diverticula are reported and this condition is discussed
based on a literature review.

CASES REPORT

Case 1) A 72 years old female complaining abdominal
pain in the left-lower quadrant for two weeks. Pain usually was relieved after
evacuations. She had medical history of obesity, arterial hypertension and had
a prior hemorrhoidectomy. Flexible retossigmoidoscopy revealed multiple diverticula
in sigmoid and a diverticulum in the right lateral wall of the rectum with an
ostium of 3 cm. Abdominal computed tomography and barium enema showed diverticular
disease of transverse and sigmoid colon, as well as the rectal diverticulum.

Case 2) A 59 years old female suffering from
pain in the left-lower quadrant of abdomen and diarrhea alternating to constipation
for two years. Exception for obesity she had no significant medical history.
Colonoscopy showed diverticular disease of descending and sigmoid colon associated
with a diverticulum in the posterior wall of rectum. This diverticulum had an
unusual small ostium (0.7cm), a central depression and elevated margins.

Case 3) A 77 years old male presenting constipation
and rectal pain for two weeks. Medical history revealed chagasic megacolon corrected
by Duhamel's technique 14 years ago. He was a smoker and presented hypothyroidism,
hypertension and diabetes mellitus. Colonoscopy showed rectal atony and dilatation,
anatomical modifications from Duhamel's surgery and a rectal diverticulum with
an ostium diameter of 2.5 cm in the posterior wall.

Case 4) A 56 years old male with recurrent episodes
of severe pain in anal region, associated with constipation for six months.
He also complained urinary alterations. He was a smoker and had no previous
medical records. Barium enema and abdominal computed tomography showed diverticular
disease of descending and sigmoid colon and a rectal diverticulum in the anterior
wall of the rectum (Figure 1).

Flexible retossigmoidoscopy confirmed the large
rectal diverticulum filled with fecaloma and an ostium diameter of 3 cm.

A pelvic ultrasound showed that the rectal diverticulum
was 5.3 cm wide and it was compressing the bladder (Figure 2).

The patient underwent surgery and a single diverticulectomy
was performed. Analysis of the resected diverticula revealed normal colonic
tissue. One year and six months after diverticulectomy the patient was totally
asymptomatic.

DISCUSSION

Rectal diverticula are rare. Most cases are asymptomatic
and the finding is incidental. The true prevalence of this condition is hard
to define. In a 4.854 barium enema, Walstad et al.14 found 0.08%
of prevalence in all exams. Other series revealed a prevalence of 2% to 2.4%
in patients with diverticular disease of the colon12,14. The most
affected age group is from 55 to 85 years, and male patients are three times
more affected1. The ten years prevalence of rectal diverticula in
authors endoscopy unit is 0.15% of all colonoscopies, and 0.74% in patients
with colonic diverticulosis.

Theories to explain the low prevalence of the
rectum diverticula have been proposed. Anatomical disposition of the muscle
layers on the rectum, especially in the anterior and posterior walls, promoting
a major resistance to intraluminal variations could justify the lower prevalence
of this condition compared to colonic diverticulosis15. Less intense
rectal pressure and lesser peristaltic movements than sigmoid could be other
reason to this low prevalence1,3. A report of rectal diverticulum
in a newborn raises the possibility of this condition being congenital. This
congenital theory is reinforced by the similarity with the diverticular form
of the congenital duplication of the rectum7.

Rectal diverticula generally are unique, but
cases of three diverticula in the same rectum have been reported1.
In most cases the ostium diameter is 2 cm or more, while colonic diverticula
generally present smaller ostium diameters ranging from 0.5 to 1.0 cm1,10.
In contrast to colonic diverticulum, rectum diverticulum contains all wall layers;
therefore it is considered a true diverticulum4. Usually rectal diverticulum
is presented at endoscopic examination as a large ostium with communication
to the rectum lumen in the lateral walls of the rectum9,11,12,14.
They are often associated with diverticulosis and patient complaints are usually
due to the colonic disease10. These four patients had diverticular
disease of colon with the sigmoid affected in all cases.

Diverticula may manifest as diverticulitis, infections,
ulceration, perforation, fistula, prolapse or perineal mass14. Diverticulitis
occurs due to fecal impaction, trauma or other irritants. Infection leads to
abscess formation if not treated properly. Perforation may occur, however it
is less troublesome when compared with perforation of the colonic diverticula
because they are located underneath the peritoneal reflection1,8.
Both infection and perforation may result in fistula7. Large abnormal
diverticula may prolapse through the anus or produce a perineal mass that enlarges
during evacuation2,5. In this series, one patient presented rectal
diverticulum with recurrent diverticulitis. The large fecaloma inside the diverticulum
was the possible explanation for diverticulitis. This patient also had recurrent
urinary changes caused by bladder compression as demonstrated by ultrasound.

Some factors such as obesity, constipation and
recurrent fecal impaction are associated with the presence of rectal diverticula
probably because those conditions could increase rectal pressure. However, Martinez
et al studied patients with rectal diverticula with anorectal manometry and
found no changes in normal-pattern of the sphincter pressures, rectal sensitivity
or complacence. Absence of supportive structures as coccyx, rectal infections
or trauma, hemorrhoids, muscular atrophy or degenerative genetic anomalies are
also considered risk factor for the occurrence of rectal diverticulum8,14,15.

Usually rectal diverticula need no surgical treatment
since most cases are asymptomatic. Periodic follow-up is recommended due to
possible metaplastic and posterior malignancy changes in the mucosa2,3,14.

Surgical intervention is reserved to symptomatic
diverticulum or complications. The approach depends on the gravity or extension
of the disease. Local drainage, diverticula invagination and diverticulectomy
are preferred in single or located complications. Aggressive surgical procedures
as retosigmoidectomy or abdominoperineal amputation are reserved for extent
complicated disease or when malignancy is recognized3,8. In one of
these patients a single diverticulectomy was performed because of the recurrent
episodes of pain and located diverticulitis. He also presented bladder-compression
symptoms. The surgery was effective and one year and six months after that the
patient was totally asymptomatic.